Reciprocating engine

ABSTRACT

A reciprocating engine, particularly a steam engine having at least two cylinders, wherein the valving operation is achieved by means of slots in pistons co-acting with valving ports in cylinder walls of the engine.

United States Patent 310,369 l/1885 Bown ...91/1s4 Peoples [451 Apr. 4, 1972 [54] RECIPROCATING ENGINE 654,127 7/1900 Billetop ..91/ 184 1,049,076 12/1912 Gjerde.... .....91/l91 Invenwfl J y Peoples, 2419 Greenhfll Drive, 2,225,372 12/1940 Elm ..91/191 Huntsville, Ala. 35810 Prima Examiner-Paul E. Maslousk 1 a; F b. 27 1970 Y [22] e e AttomeyC. A. P111111, [21] Appl. No.: 15,086

[57] ABSTRACT [52] U.S. Cl ..91/184, 91/ 191 A reciprocating engine, particularly a steam engine having at [51] least two cylinders, wherein the valving operation is achieved [58] Field of Search ..91/184, 191, 192 y m ans f slo s in pis ns co-acting with valving ports in cylinder walls of the engine. [56] Relerences Cited 7 C 130" I ll UNITED STATES PATENTS PATENTED PR 41912 I 7 3,653,297

sum 1 or 5 FIG. 2 Jerry A. Peoples,

INVENTOR PATENTEBAPH 4 I972 3, 6 53,2 97

BY Kd/Mw ATTORNEY PATENTEDAPR 4 I972 SHEET 0F 5 FIG. 7

Jerry A.Pedp|es,

INVENTOR FIG. 8

RECIPROCATING ENGINE This invention relates to reciprocating engines and particularly to valving systems for communicating flow of gases into and out of such engines.

Reciprocating engines, which are powered by the application of gases under pressure, such as steam engines, require some form of auxiliary apparatus to commutate flow between cylinders. Almost invaribly this has involved the use of sliding port type apparatus which after some wear permitted leakage of pressure into the atmosphere. This leakage of course represents loss and reduced efficiency in the system as a whole. Today, there is renewed interest in steam engines for use in automobiles and other new applications, but the requirements of engines in these new applications are severe. First, it is generally agreed that the system should be a closed system and as such should be substantially immune from leakage of steam. This is particularly the case because of the use of new and often expensive fluids in place of water. Another requirement which is not necessarily new, is that in order to assure lowest cost the engine should be simple having as few parts as possible.

Accordingly, it is an object of this invention to provide a generally improved gas operated engine.

It is a further object of this invention to provide an improved steam engine which is capable of reduced steam leakage.

It is a further object of this invention to provide a gas pressure operated multi-cylinder reciprocating engine which does not employ separate commutating valves.

It is still a further object of this invention to provide a multicylinder steam reciprocating engine wherein both pressure intake and exhaust are commutated through a valving system which utilizes only the engine pistons and valving ports to achieve steam flow into the engine over selected portions of cutoff.

lt is still another object of this invention to provide a multicylinder steam reciprocating engine wherein steam inlet and exhausting is commutated by means of valving ports co-acting grooves and the engine pistons and whereas exhausting is supplemental by means of the uniflow technique.

In accordance with the invention, a reciprocating engine would have an even number of cylinders and each pair of cylinders would have a cooperative system of valving wherein gas pressure for one cylinder would pass through valving channels of the other cylinder and vice versa. The pistons of such of a pair of cylinders are eccentrically operated on a crank shaft so that their strokes are approximately 90 displaced. Actually this difference may be within a practical range which extends from about 60 to 120. By operating the pistons of each cylinder in an offset manner such as this and wherein each piston is moving other than along an identical or reciprocal path of position at any one time, a path or channel for control flow to one cylinder is arranged by utilizing pistons as valves wherein the piston of one cylinder occultus the fiow to the other cylinder during the up-stroke portion of its stroke when it must exhaust from the previous stroke but enables flow during the top portion of the down-stroke when flow is desired. The actual path of flow to each cylinder thus passes through two valves, one associated with each cylinder and this is the case for both cylinders. Thus, steam flow to cylinder (A) passes through a slot valve system of cylinder (B) and slot valve system of cylinder (A) before reaching an intake port at the top of cylinder (A) and, the same is true of cylinder (B) wherein steam flow is through a slot valve system of cylinder (A) and a slot valve system of cylinder (B) before reaching the intake of cylinder (B). Where it is desired to effect exhaust flow during the tip-stroke of a piston rather than to depend solely upon unifiow exhaust, a slot valve system is provided for exhaust flow which is similar to the steam intake valving system described above.

These and other objects, features and advantages of the invention will become more apparent from the description when considered together with the drawings in which:

FIG. 1 is a pictorial view, partially schematic, of a two cylinder version of the invention;

FIG. 2 is a perspective view of a piston showing slots used in the valving system of the invention;

FIGS. 3-8 are schematic illustrations of the engine at successive stages of operation;

FIG. 9 is a schematic illustration of a modified valving system wherein means are provided for selectively extending steam cutoff; and

FIGS. 10a-l0c are schematic illustrations showing the portslot arrangement employed in the system of FIG. 9 at different points of piston travel.

Referring to the drawings and initially to FIGS. 1-2, there is shown the general configuration of the valving system of this invention. It is to be noted that in the following description there is contained at the end a glossary of terms as a cross reference between specification language and claim language. In addition, in the first instance in which a term is used in the specification and there exists a cross reference term in the claims, the cross reference is indicated in parenthesis. The position of engine components at progressive stages during a cycle of operation is shown in FIGS. 3-8. These drawings illustrate by way of example an engine with a cutoff of approximately 20 percent of the power stroke. Lower or higher values of cutoff are, of course, feasible, as well as multiple values of cutoff as will be described with respect to an additional embodiment of the invention. As shown in FIGS. 3-8, identical pistons 10 (first piston) and 12 (second piston) of cylinders 14 (first cylinder) and 16 (second cylinder) of engine 18 have throws differing by approximately with the shape of piston 10 leading piston 12. The respective connecting rods 20 (first connecting rod) and 22 (second connecting rod) are connected by a conventional crankshaft, diagrammatically illustrated by broken line 24. Pistons 10 (FIG. 2) and 12 are longer than in conventional reciprocating engines and each includes a plurality of slots which coact with ports in cylinders 14 and 16 to perform both steam intake and exhaust commutation. The valving structure to achieve intake commutation is described first.

Valve assembly 26, consisting of slot 27 (second elongated groove) in piston 10 and cooperating ports 28 (a) and 29 (b) in cylinder 14, controls or times intake flow between channels 30 (third channel) and 32 (fourth channel), and thus flow to cylinder 14 through port 33 (first inlet port). Valve assembly 26 thus determines the portion of downstroke of piston 10 during which steam is admitted to cylinder 14, or cutoff. Valve assembly 34, consisting of slot 36 (first elongated groove) in piston 10 and ports 38 (a) and 40 (b) in cylinder 14 controls flow between channels 42 and 44 (first channel) and is adapted to occult steam flow to cylinder 16 during up-stroke travel of piston 12. Valve assembly 46, consisting of slot 48 (third elongated groove) in piston 12 and cooperation ports 50 and 52 (third pair of valving ports a and b) in cylinder 16, controls or times intake flow between channels 44 and 56 (second channel) and thus to cylinder 16 through port 57 (second inlet port). Valve assembly 58 consists of slot 60 (fourth elongated groove) in piston 12 and cooperating port 62 and 64 (fourth pair of valving ports a and b) in cylinder 16 to control flow between channels 42 and 30 and is adapted to occult steam flow to cylinder 14 during up-stroke travel of piston 10.

Similar valve assemblies provide commutation of engine exhaust permitting exhaust flow during the up-stroke of each piston. Thus, valving assembly 68, consisting of slot 70 (sixth elongated groove) in piston 10 and cooperating ports 72 and 74 (sixth pair of valving ports a and b) in cylinder 14, controls or times flow between channels 76 (eighth channel) and 78 (seventh channel) and thus exhaust flow from exhaust port 75 (first outlet port) in cylinder 14. Thus exhaust flow from cylinder 14 is timed for a precise portion of the up-stroke of piston 10. Valve assembly 80, consisting of slot 82 (fifth elongated groove) in piston 10 and cooperating ports 84 and 86 (fifth pair of valving ports a and b) in cylinder 14 controls flow between channels 88 (fifth channel) and 90 and is adapted to occult the exhaust flow from cylinder 16 during down-stroke of piston 12. Valve assembly 92, consisting of slot 94 (seventh elongated groove) and cooperating ports 96 and 98 (seventh pair of valving ports a and b) controls or times flow between channels 100 (sixth channel) and 88 and exhaust flow from exhaust port 101 (second outlet port) in cylinder 16 is timed for a precise portion of the up-stroke of piston 12. Valve assembly 102, consisting of slot 104 (eighth elongated groove) in piston 12 and cooperating ports 106 and 108 (eighth pair of valving ports a and b) in cylinder 16 controls flow between channels 78 and 90 and is adapted to occult the exhaust flow from cylinder 14 during the downstroke of piston 10.

As shown in FIG. 2, intake valving slots 27 and 36 in piston and like grooves in piston 12, not shown, are spaced about the skirt of each piston and are typically 0.06 inch in depth. They, of course, do not go through the wall. With respect to the piston 12, slot depths are the same lengths and the length of intake slot 48 is the same as intake slot 27 and the length of exhaust slot 94 is the same as exhaust slot 70. However, intake slot 60 is slightly longer than slot 36 and exhaust slot 104 is identical with respect to exhaust slot 82. Also, as shown, due to the non-reciprocal relationship between travel of pistons 10 and 12 which are related by about 90 rather than 180, the longitudinal slot positions of intake slots 36 and 60 and exhaust slots 82 and 104 differ. These slots are positioned to enable flow only when required and to block flow at other times as otherwise described herein.

To examine operation of the engine and referring particularly to FIGS. 3-8, assume that the pistons are initially in the position shown in FIG. 3. In this position it will be noted that piston 10 is at top dead center, that piston 12 is at a position below cutoff on its downward stroke, and intake valve assembly 58 operates as follows. As shown, slot 60 has just uncovered ports 62 and 64 and steam passes from supply channel 42 to port 62, then through slot 60, port 64 and channel 30 to port 28 of cylinder 14. Input valve assembly 26 is also operated open as slot 27 of piston 10 has also just uncovered ports 28 and 29. Thus steam continues through port 29 and channel 32 to port 33 in the top of cylinder 14 which opens into the top chamber of cylinder 14. As slots 36 and 48 are not in cooperative ports, steam flow is occulted from cylinder 16. As exhaust slot 70 is not in cooperative engagement with its coordinate ports, exhaust flow from cylinder 14 is occulted and as both slots 82 and 94 are not in cooperative engagement with their respective coordinate ports, exhaust flow from cylinder 16 is also occulted. Thus, the only flow that can occur into and out of either cylinder is the intake flow into cylinder 14. Thus steam pressure is applied to piston 10 to move it downstroke, or to the right, as shown. At the same time, piston 12 is also being moved to the right under steam pressure previously admitted to cylinder 16.

FIG. 4 shows the engine after approximately 45 of rotation and wherein slot 27 of piston 10 is just passing to the right of ports 28 and 29 cutting off flow of steam between channels 30 and 32 and thus flow to cylinder 14. It is to be noted also that slot 60 is just passing to the right of ports 62 and 64 and thus flow between channels 42 (a) and 30 is also being cut off. It is not necessary, however, that slot 60 perform a cutoff role at this point as its general function is to prevent flow to cylinder 14 when slot 27 otherwise would permit flow during the upstroke of piston 10, which would be undesirable.

It is to be further noted from FIG. 4 that piston 12 is nearing the bottom dead center and that exhaust flow from cylinder 16 has commenced. Referring to FIG. 4, slots or ports are cut through the cylinder wall as represented by port 112. This port is located near the working bottom of the cylinder such that it is always occulated by piston 12 whenever the crank is off bottom dead center i 20. As the piston passes through bottom dead center port 112 is not occulated by piston 12, thus allowing the expanded steam to flow from cylinder 16 through port 1 12. Exhaust flow is also ported through port 101 in the top of cylinder 16. From the latter, auxiliary exhaust port, flow is through channel 100, port 96, slot 94, port 98, channel 88, port 86, slot 82 and exhaust channel 90. Uniflow ports 112 (exhaust means) (FIG. 4) and 110 (exhaust means) (FIG. 5)

are the primary exhausting means. The auxiliary exhaust route allows venting during the return stroke of pistons 10 and 12. Thus, compression pressures are kept to a minimum.

Referring next to FIG. 5, there has now occurred 180 of rotation of engine 18 and piston 10 has now moved to bottom dead center. Uniflow exhaust port 110 is uncovered and it provides the primary exhaust flow means from cylinder 14 during the limited portion of the stroke while port 110 is not occulted. In addition to exhaust flow through exhaust port 1 l0, and with pistons 10 and 12 as shown, with both pistons on an up-stroke, exhaust slots (piston 10) and 104 (piston 12) are in a position to permit exhaust flow from exhaust port in the top of cylinder 14. Exhaust thus commences and flows through valve assemblies 68 and 102. Flow is then through channel 75, ports 74, slot 70, port 72, channel 78, port 106, slot 104, port 108, to exhaust channel 90. Thus cylinder 14 continues to exhaust for most of the up-stroke of piston 10.

While piston 10 is moving upward, to the left, from bottom dead center, piston 12 is likewise moving upward and cylinder 16 is exhausting through valve assemblies 92 and and channels 100, 88 and 90. In this case, flow is from exhaust port 101 through channel 100, port 96, slot 94, port 98, channel 88, port 86, slot 82 to exhaust channel 90.

FIG. 6 shows the posture of the engine with piston 10 approximately halfway up on its upstroke and piston 12 at essentially top dead center. At this point no valving action occurs with respect to cylinder 14 as it merely continues to exhaust through valve assemblies 68 and 102, however, there is a changed condition with respect to cylinder 16 in that exhaust valve assemblies 92 and 80 are now occulted and valve assemblies 34 and 46 open to prepare cylinder 16 for a power stroke.

FIG. 7 shows conditions about 45 later. Considering first the operation of cylinder 16 and piston 12, input valve assemblies 34 and 46 are open and have been open for the past 45 of rotation but are now at a point at which cutoff to cylinder 16 commences. At the same time exhaust valve assemblies 68 and 102 commence cutting off exhaust flow from cylinder 14, occurring just before piston 10 reaches top dead center. This completes one cycle or revolution of operation.

FIG. 8 shows the status of operating components 135 later, there having occurred in the interim steam inlet flow through valve assemblies 58 and 26 to cylinder 14 and, as shown now, cutoff of these valve assemblies has occurred. Piston 12 of cylinder 16 is at bottom dead center with uniflow exhaust port 112 open and exhaust valve assemblies 92 and 80 just commencing to open to permit continued exhaust during the upstroke of piston 12.

As shown in FIGS. 4 to 9, the intake and exhaust valve assemblies are illustrated schematically as being longitudinally displaced. This was done to separate the valve assemblies for purposes of illustrations only. Actually they would be located approximately at the same longitudinal position in order to keep piston skirt lengths to a minimum, as shown in FIG. 1.

FIGS. 9 and 10 illustrate schematically a modification of the valving system shown in the previous figures. As only the input valve assemblies are affected, the exhaust system is not shown. As modified, the input valve assemblies, shown as valve assemblies and 122 provide means for selectively extending cutoff. As stated above, the cutoff illustrated in FIGS. 3 to 8 are set at about 20 percent, that is input valve assemblies 26 and 46 permit steam intake flow for about 20 percent of the down-stroke of pistons 10 and 12. While this is an acceptable value for general purpose operation, there are applications where, due to varying load conditions, such as in the case of an automobile during acceleration, additional torque is needed. Under such conditions it becomes desirable to delay cutoff to apply steam for a longer portion of the power stroke. Likewise, it is desirable to be able to shift back to a lower figure of cutoff as soon as torque requirements lessen. As particularly shown in FIG. 10, valve assemblies 120 and 122 include irregular slots 124 (piston 125) and 126 (piston 127), each being of greater length on one side (length being the vertical dimension in FIG. than on the other. Additional ports 128 and 129 (auxiliary ports) are fed through central valves 130 and 132 (control means), respectively, and thus, as shown in FIG. 10a when port 128 (auxiliary port), in the case of piston 125, is uncovered, it provides steam flow from port 128 to slot 124. Then, after regular port 128 has been covered and steam flow would have otherwise been cut off (and the same for piston 127 during its power stroke) valves 130 (control means) and 132 and cooperative ports 128 and 129 provide flow to their respective cylinders 134, and 136 (control valve), for an extended portion of their stroke. As illustrated in FIG. 10 this would be for approximately an additional percent of the stroke, thus extending cutoff for a total of 40 percent of the power stroke. Initially, as shown in FIG. 10a, regular ports 28 and 29 are uncovered by slot 124 and this continues for about 20 percent of the stroke. Next, as shown in FIG. 10b, regular input port 28 is covered but added port 128 is uncovered and, with valve 130 operated, intake flow will continue for the added portion of stroke. Finally, as shown in FIG. 10c, all ports are uncovered to produce cutofi. The

same pattern occurs for cylinder 134 as valve 130 and 132 are operated in unison by valve control 136.

In order for the modified pistons 125 and 126 to operate properly, slots 138 and 140 must be sufficiently long that they will permit steam flow to channels 30 and 44 for sufficient portion of the travel of pistons 125 and 127. While as shown in FIG. 10, the reference is to piston 125 of cylinder 134, the same general explanation holds with respect to piston 127 of cylinder 136.

In order to facilitate an understanding of the references in the claims, cross-references are set forth as follows as examples:

l first cylinder-cylinder 14;

first inlet portport 33;

one end of first cylinderleft end as shown in FIG. 3;

first pair of valving ports a and b-port 38 is port a and port 40 is port b;

second pair of valving ports a and b-port 28 is port a and port 29 is port b;

first pistonpiston 10;

first connecting rodconnecting rod 20;

first elongated groovegroove 36;

second elongated groovegroove 27;

second cylinder-cylinder 16;

one end of second cylinder-left end of cylinder 16;

second inlet portinlet port 57;

third pair of valving ports a and b-port 50 is port a and port 52 is port b; fourth pair of valving ports-port 62 is port a and port 64 is port b;

second pistonpiston 12;

second connecting rod-connecting rod 22;

third elongated groovegroove 48;

fourth elongated groovegroove 60;

exhaust meanse.g. exhaust ports 1 10 and 112;

first channel-channel 44;

second channelchannel 56;

third channel-channel 30;

fourth channel-channel 32;

auxiliary porteg. port 128 or port 129, one of the other of said ports (claim 3)e. g. port 28 control means-cg. valve 130 or valve 132 and these valves as controlled by control valve 136;

first outlet portoutlet port 75;

second outlet portoutlet port 101;

fifth pair of valving ports a and bport 84 is port a and port 86 is port b; sixth pair of valving ports a and bport 72 is port a and port 74 is port b;

fifth elongated groovegroove 82;

sixth elongated groovegroove 70;

seventh pair of valving ports a and b-port 96 is port a and port 98 is port b;

eighth pair of valving ports a and b-port 106 is port a and port 108 is port b;

seventh elongated groovegroove 94;

eighth elongated groovegroove 104;

fifth channel-channel 88;

sixth channel-channel seventh channel-channel 78; and

eighth channel-channel 76.

There has been described above a unique system of valving which eliminates the need of distinct valves, as well as cam shafts and push rods required to drive them. Further, the structure of the engine of this invention is inherently simple and economical to construct. Further, in addition to the reduction of number of parts, the problem of valve lubrication for several points, as would normally be required with mechanically driven valves, is eliminated. Further, the lubrication of pistons is facilitated in that as the grooves or slots slide past a portion of a cylinder sleeve they are coated with oil from the crankcase brought up during the last up-stroke. Further, lubrication is distributed by virtue of a small portion of oil being squeezed into slots 36 and 60 and being blown in the opposite cylinder through channels 44 or 30. Thus, a portion of each cylinder becomes lubricated by active means. Metering of the amount of oil being squeezed into the flow slots can be controlled by the length of the piston skirt and tolerances placed on the cylinder and piston diameters.

lclaim:

l. A reciprocating engine comprising at least one pair of dual cylinder assemblies wherein each cylinder assembly comprises:

A. a crank shaft and first and second connecting rods connected thereto, the angular relation of connection of said connecting rods to said crankshaft and orientation of said cylinder assemblies being arranged whereby the motion of said connecting rods differ by not less than 60 and not more than B. a first cylinder generally enclosed at one end, having a first inlet port at said one end and first and second pairs of valving ports a and b intermediate the ends of said first cylinder;

C. a first piston connected to be reciprocately operated by said first connecting rod in said first cylinder and having first and second elongated grooves in the surface thereof, said first groove being positioned and of a length adapted to connect and disconnect said first pair of valving ports during a predetermined portion of the stroke of said first piston and said second groove being positioned and of a length to connect and disconnect said second pair of valv ing ports during a predetermined portion of the stroke of said first piston;

D. a second cylinder generally enclosed at one end, having a second inlet port at said one end and third and fourth pairs of valving ports a and b intermediate the ends of said second cylinder;

E. a second piston connected to be reciprocately operated by said second connecting rod in said second cylinder and having third and fourth elongated grooves in the surface thereof, said third elongated groove being positioned and of a length to connect and disconnect said third pair of ports during a predetermined portion of the stroke of said second piston and said fourth elongated groove being positioned and of a length to connect and disconnect said fourth pairs of ports during a predetermined portion of the stroke of said second piston;

F. exhaust means connected to each said cylinder for exhausting a said cylinder for a predetermined portion of the stroke of each said piston; and

G. a first channel connecting port b of said first pair of valving ports to port a of said third pair of valving ports, a second channel connecting port b of said third pair of valving ports to said second inlet port, a third channel connecting port b of said fourth pair of valving ports to port a of second pair of valving ports, and a fourth channel connecting port b of said second pair of valving ports to said first inlet port, whereby said engine is operated by the application of the source of gas pressure to the other of said first and fourth pairs of valving ports.

2. A reciprocating engine as set forth in claim 1 wherein the length of said second and third elongated grooves are adjusted to limit flow to said inlet ports to between percent and 45 percent of the stroke from top dead center.

3. A reciprocating engine as set forth in claim 1 further comprising means for selectively extending the point of cutoff of gas flow to at least one cylinder over a longer portion of its power stroke comprising:

A. an auxiliary port connected to at least one of said cylinders and adapted to communicate with one of said grooves of the said piston of said last named cylinder after one of the other of said ports adapted to communicate with said last named groove is disconnected during normal operation; 7

B. control means for selectively interconnecting said auxiliary port to the said channel which is connected to said last named one of the other of said ports;

C the groove in the piston of said cylinder which is adapted to communicate with said last named channel being of such length as to enable gas flow during the period when said auxiliary port is uncovered by said last named groove and after the last named one of the other of said ports is covered,

whereby gas pressure cutoff to said last named cylinder may be selectively extended to increase power of said engine.

4. A reciprocating engine as set forth in claim 3 wherein:

A. said at least one cylinder is said first cylinder;

B. said auxiliary port is in said first cylinder; and

C. said auxiliary port is adapted to communicate with said second groove.

5. A reciprocating engine as set forth in claim 4 wherein:

A. said last named channel is said third channel; and

B. said last named other said port is one of said second pairs of ports.

6. A reciprocating engine as set forth in claim 5 wherein said last named other port is port a.

7. A reciprocating engine as set forth in claim 1 wherein said exhaust means comprises:

A. first outlet port at said enclosed one end of said first cylinder and second outlet port at said enclosed end of said second cylinder;

B. said first cylinder includes fifth and sixth pairs of valving ports a and b intermediate the ends of said first cylinder; C. said first piston having fifth and sixth elongated grooves in the surface thereof, said fifth groove being positioned and adapted to connect and disconnect said fifth pair of valving ports during a predetermined portion of the stroke of said first piston and said sixth groove being positioned and adapted to connect and disconnect said sixth pair of valving ports during a predetermined portion of the stroke of said first piston;

D. said second cylinder includes seventh and eighth pairs of valving ports a and b intermediate the ends of said second cylinder;

E. said second piston having seventh and eighth elongated grooves in the surface thereof, said seventh elongated groove being adapted and positioned to connect and disconnect said seventh pair of ports during a predetermined portion of the stroke of said second piston and said eighth elongated groove being adapted and positioned to connect and disconnect said eighth pair of ports during a predetermined portion of stroke of said second piston; and

F. a fifth channel connecting port a to said fifth pair of valving ports to port b of said seventh pair of valving ports, a sixth channel connecting port a of said seventh pair of valving ports to said second outlet port, a seventh channel connecting port a of said eighth pair of valving ports to port b of said sixth pair of valvlng ports, and an eighth channel connecting port a of said sixth pair of valving ports to said first outlet port,

whereby each cylinder of said cylinder assembly is exhausted through said outlet port during the up-stroke of the piston of that cylinder. 

1. A reciprocating engine comprising at least one pair of dual cylinder assemblies wherein each cylinder assembly comprises: A. a crank shaft and first and second connecting rods connected thereto, the angular relation of connection of said connecting rods to said crankshaft and orientation of said cylinder assemblies being arranged whereby the motion of said connecting rods differ by not less than 60* and not more than 120*; B. a first cylinder generally enclosed at one end, having a first inlet port at said one end and first and second pairs of valving ports a and b intermediate the ends of said first cylinder; C. a first piston connected to be reciprocately operated by said first connecting rod in said first cylinder and having first and second elongated grooves in the surface thereof, said first groove being positioned and of a length adapted to connect and disconnect said first pair of valving ports during a predetermined portion of the stroke of said first piston and said second groove being positioned and of a length to connect and disconnect said second pair of valving ports during a predetermined portion of the stroke of said first piston; D. a second cylinder generally enclosed at one end, having a second inlet port at said one end and third and fourth pairs of valving ports a and b intermediate the ends of said second cylinder; E. a second piston connected to be reciprocately operated by said second connecting rod in said second cylinder and having third and fourth elongated grooves in the surface thereof, said third elongated groove being positioned and of a length to connect and disconnect said third pair of ports during a predetermined portion of the stroke of said second piston and said fourth elongated groove being positioned and of a length to connect and disconnect said fourth pairs of ports during a predetermined portion of the stroke of said second piston; F. exhaust means connected to each said cylinder for exhausting a said cylinder for a predetermined portion of the stroke of each said piston; and G. a first channel connecting port b of said first pair of valving ports to port a of said third pair of valving ports, a second channel connecting port b of said third pair of valving ports to said second inlet port, a third channel connecting port b of said fourth pair of valving ports to port a of second pair of valving ports, and a fourth channel connecting port b of said second pair of valving ports to said first inlet port, whereby said engine is operated by the application of the source of gas pressure to the other of said first and fourth pairs of valving ports.
 2. A reciprocating engine as set forth in claim 1 wherein the length of said second and third elongated grooves are adjusted to limit flow to said inlet ports to between 5 percent and 45 percent of the stroke from top dead center.
 3. A reciprocating engine as set forth in claim 1 further comprising means for selectively extending the point of cutoff of gas flow to at least one cylinder over a longer portion of its power stroke comprising: A. an auxiliary port connected to at least one of said cylinders and adapted to communicate with one of said grooves of the said piston of said last named cylinder after one of the other of said ports adapted to communicate with said last named groove is disconnected during normal operation; B. control means for selectively interconnecting said auxiliary port to the said channel which is connected to said last named one of the other of said ports; C. the groove in the piston of said cylinder which is adapted to communicate with said last named channel being of such length as to enable gas flow during the period when said auxiliary port is uncovered by said last named groove and after the last named one of the other of said ports is covered, whereby gas pressure cutoff to said last named cylinder may be selectively extended to increase power of said engine.
 4. A reciprocating engine as set forth in claim 3 wherein: A. said at least one cylinder is said first cylinder; B. said auxiliary port is in said first cylinder; and C. said auxiliary port is adapted to communicate with said second groove.
 5. A reciprocating engine as set forth in claim 4 wherein: A. said last named channel is said thiRd channel; and B. said last named other said port is one of said second pairs of ports.
 6. A reciprocating engine as set forth in claim 5 wherein said last named other port is port a.
 7. A reciprocating engine as set forth in claim 1 wherein said exhaust means comprises: A. first outlet port at said enclosed one end of said first cylinder and second outlet port at said enclosed end of said second cylinder; B. said first cylinder includes fifth and sixth pairs of valving ports a and b intermediate the ends of said first cylinder; C. said first piston having fifth and sixth elongated grooves in the surface thereof, said fifth groove being positioned and adapted to connect and disconnect said fifth pair of valving ports during a predetermined portion of the stroke of said first piston and said sixth groove being positioned and adapted to connect and disconnect said sixth pair of valving ports during a predetermined portion of the stroke of said first piston; D. said second cylinder includes seventh and eighth pairs of valving ports a and b intermediate the ends of said second cylinder; E. said second piston having seventh and eighth elongated grooves in the surface thereof, said seventh elongated groove being adapted and positioned to connect and disconnect said seventh pair of ports during a predetermined portion of the stroke of said second piston and said eighth elongated groove being adapted and positioned to connect and disconnect said eighth pair of ports during a predetermined portion of stroke of said second piston; and F. a fifth channel connecting port a to said fifth pair of valving ports to port b of said seventh pair of valving ports, a sixth channel connecting port a of said seventh pair of valving ports to said second outlet port, a seventh channel connecting port a of said eighth pair of valving ports to port b of said sixth pair of valving ports, and an eighth channel connecting port a of said sixth pair of valving ports to said first outlet port, whereby each cylinder of said cylinder assembly is exhausted through said outlet port during the up-stroke of the piston of that cylinder. 